<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        span{
            color:red;
        }
    </style>

    <link href="../css/demo.css" rel="stylesheet
">
</head>
<body>
<div style="color:red">hello css</div>
<span>hello css</span>
<p>hello css</p>
</body>
</html>